Question

I am trying to animate an object, let’s say its a car. I want it go from point

x1,y1,z1

to point x2,y2,z2 . It moves to those points, but it appears to be drifting rather than pointing in the direction of motion. So my question is: how can I solve this issue in my updateframe() event? Could you point me in the direction of some good resources?

Thanks.

Answer 1

First off how do you represent the road?

I recently done exactly this thing and I used Catmull-Rom splines for the road. To orient an object and make it follow the spline path you need to interpolate the current x,y,z position from a t that walks along the spline, then orient it along the Frenet Coordinates System or Frenet Frame for that particular position.

Basically for each point you need 3 vectors: the Tangent, the Normal, and the Binormal. The Tangent will be the actual direction you will like your object (car) to point at.

I choose Catmull-Rom because they are easy to deduct the tangents at any point – just make the (vector) difference between 2 other near points to the current one. (Say you are at t, pick t-epsilon and t+epsilon – with epsilon being a small enough constant).

For the other 2 vectors, you can use this iterative method – that is you start with a known set of vectors on one end, and you work a new set based on the previous one each updateframe() ).